1. Field of the Invention
The present invention relates to a novel catalyst useful as homogeneous hydrogenation, in particular as homogeneous asymmetric hydrogenation and, in detail, a process for producing a hydrogenated compound of an unsaturated compound, in particularly, an optically active compound using said catalyst.
2. Related Art
Recently, synthesis methods using copper as a catalyst have been widely studied in the field of asymmetric synthesis.
For example, WO01/19761 describes the asymmetric hydrosilylation of α,β-unsaturated ester. The method described in WO01/19761, however, has such problems that a silyl ether form of the above-mentioned α,β-unsaturated ester need to form and is necessary for an acid or alkali treatment to obtain the objective compound, therefore the method becomes to complicate operation, and result in high costs because a silane waste is produced in an equivalent or more amount theoretically, further a silane compound as a reducing agent used in hydrosilylation is highly expensive as compared with hydrogen gas.
U.S. Pat. No. 3,732,329 describes the hydrogenation of olefins by using a complex obtained by reacting copper(I) chloride with a phosphorus compound. In this U.S. Pat. No. 3,732,329, however, the phosphorus compound allowed to react with copper (I) chloride is not a chiral compound and the resulting complex is not a chiral complex, and there is no description of a reaction of a chiral ligand with a copper compound. Accordingly, the hydrogenation of the olefins described in this U.S. Pat. No. 3,732,329 is not an asymmetric hydrogenation.
React. Kinet. Catal. Lett., Vol. 9, No. 1, 73 (1978). describes the asymmetric hydrogenation of ethyl acetoacetate and acetylacetone by using a complex obtained from Raney copper and an optically active amino acid. However, the asymmetric hydrogenation described in this literature is a heterogeneous system. Accordingly, the literature has such problems that the reaction solution does not become homogeneous and the method described in this literature becomes inferior workability because Raney copper is required careful handling etc. In the reaction described in this literature, the catalyst activity and the asymmetric yield in the reaction system are extremely low and do not reach a practical level.
JP-A-54-39052 and J. Org. Chem., 45, 2995 (1980). describe that a rhodium complex is obtained by reacting a specific bisphosphine ligand with a copper salt to produce a chiral copper complex once, and then the resulting copper complex is reacted with a rhodium complex to carry out copper-rhodium metal exchange reaction. They also describe an asymmetric hydrogenation using the resulting rhodium complex in a homogeneous system. However, in the method described in JP-A-54-39052, there is no description of an asymmetric hydrogenation using the copper complex as a catalyst, and the copper complex is used for only isolation and formation of the phosphine ligand. The catalyst species described in JP-A-54-39052 and J. Org. Chem., 45, 2995 (1980) are rhodium/phosphine complexes obtained by the metal exchange reaction. They have such problems that the methods described therein must be synthesized the copper complex first, therefore said methods become to complicate operation, in addition because rhodium is very expensive, the methods are poor economical efficiency.
Inst. Org. Khim. im. Zelinskogo, Moscow, USSR. Kinetika i Kataliz., 16(4), 1081 (1975). described an asymmetric hydrogenation using a Raney copper-ruthenium alloy and optically active tartaric acid in a heterogeneous system, and an asymmetric hydrogenation using Raney copper and optically active tartaric acid in a heterogeneous system. However, the literature has such problems that because the method described in this literature is a heterogeneous asymmetric hydrogenation, the reaction solution does not become homogeneous, and Raney copper is required careful handling, therefore becomes inferior workability, further because Ruthenium is used in addition to copper, the method is costly.
Thus there is no practical and economical asymmetric hydrogenation in a homogeneous system using a copper complex having a chiral ligand and using copper as the only transition metal participating in the asymmetric hydrogenation.